Difference Between Bright and Dark Field Microscope

The field of microbiology and bacteriology can not ply without microscopes. Science is becoming so advanced and medicines are evolving more and more effective only due to the detailed study of the microorganisms. The smallest of parts can be observed and examined with the use of microscopes and different sorts of microscopes help to gain knowledge about the different characteristics of a study sample.

Bright Field Microscope vs Dark Field Microscope

The main difference between bright and dark field microscopes is that in bright field microscopes the sample should be dark and the background of the sample needs to be bright but for dark field microscopes, the case is the exact opposite. Here the sample must be bright and the background of the sample need to remain dark.

Bright Field Microscope vs Dark Field Microscope

Bright field microscope is a very popular and common microscope that does not cost a lot. It gets used to study specimens that are transparent and needs to get stained and fixed to be observed flawlessly. The background of the sample is always needed to be bright for contrast purposes.

A sample does not need to get stained in order to be examined under a dark field microscope. However, the background of the sample must persist to be dark. This microscope is not always affordable due to its high cost and also using this microscope to examine is not very handy.

Comparison Table Between Bright and Dark Field Microscope

Parameters of ComparisonBright Field MicroscopeDark Field Microscope
Background Specimen Condition of specimen Resolution Expense Opaque disc Usability Studying mineralsIn a bright field microscope, the background remains bright.In a dark field microscope, the background is supposed to be dark.
SpecimenIts specimen is needed to be dark.Its specimen is needed to be bright.
Condition of specimenHere the specimen should be fixed and stained.Here the specimen is not needed to be stained.
ResolutionDue to the staining of the sample, the resolution gets improved.This microscope enhances the resolution without any staining.
ExpenseThese are not expensive.This microscope is quite expensive.
Opaque discThe opaque disc is not present in it.Opaque disc exists in this microscope.
UsabilityUsing this microscope is quite easy.Using this microscope is not easy.
Studying mineralsStudying minerals are not possible using this microscope.Studying minerals, crystals, metals are possible with this microscope.

What is Bright Field Microscope?

In the field of microscopes, bright field microscopes are the simplest among all the other available optical microscope options for illumination techniques. Even an amateur can use this microscope and get the work done. It does not even cost much.

It got its name from the fact that under this microscope the sample needs to have a bright field or background to appear as a dark object. Due to this the transparent specimens, get examined under this microscope. For viewing fixed specimens and live cells this gets used as they are mostly transparent. And being easy to use, this type of microscope gets adopted to teach students.

However, as staining is a must condition here, the proper process of staining should be known by the users. Also, it requires powerful light for magnification and the heat of such strong light can damage and even kill the living sample organisms.

What is Dark Field Microscope?

A dark field microscope is an expensive microscope that needs to get handled by an expert. If you want to see specimens without staining them then this microscope needs to get utilized. Under this microscope, the specimen needs to be bright and placed over a dark background.

This can be used to identify thin bacteria, algae and fungi. Living cells can be observed using this without the chances of killing it with bright light. The external structure of the sample can be seen under it.

However, dark field microscopes can also create distorted and inaccurate images. The measurement can also be faulty. It also needs to get good care. The slide, stage, and even the light source are required to be free from any sort of dust.

Capturing the accurate image, a longer time is needed. It also demands strong light which can affect and harm the observer’s eyes. Sometimes the oil or water component can form air bubbles and disrupt the study.

Main Differences Between Bright and Dark Field Microscope

  1. In a bright field microscope, the sample of the study is supposed to be dark and the background should be bright but in the case of a dark field microscope, the sample needs to be bright and the background should be dark.
  2. Using a bright field microscope is very easy but a dark field microscope is not that easily manageable.
  3. Bright field microscopes are very common and affordable but dark field microscopes are costly.
  4. For studying minerals bright field microscope is of no use but dark field microscopes can easily observe and study minerals, polymers and crystals.
  5. The study specimens of bright field microscopes must be stained but dark field microscope specimen does not require to be stained.
  6. Due to the staining, the resolution of the sample increases under a bright field microscope but under the dark field microscope, the resolution improves without staining.

Conclusion

The fields related to biology are solely dependent on microscopes as that is the only way to observe living cells, organisms and bacterias closely. As the cells and other specimens differ from each other, the need for different types of microscopes arises. Bright and dark field microscopes are two such microscopes between which bright field microscope is more common.

Both the microscopes have some advantages as well as disadvantages, so the right microscope will depend on the other available external factors. The type of specimen has a role to decide the right type of microscope to some extent. If a transparent cell is the subject of the study then a bright field microscope is sufficient but to identify bacteria one need to get support from a dark field microscope.

References

  1. https://link.springer.com/chapter/10.1007/978-3-540-70715-8_13
  2. https://ieeexplore.ieee.org/abstract/document/6588334/
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